Low pressure process for separating low boiling gas mixtures



Aug. 14, 1934. M. FRANKL LOW PRESSURE PROCESS FOR SEPARATING LOW BOILING GAS MIXTURES Filed March 19, 1930 2 Sheets-Sheet 1 I TWA- INVENTOR 7 4 45 Fl? 1.

BY i ATTIORNEYS Aug. 14, 1934. v M. FRANKL 1,970,299

I LOW PRESSURE PROCESS 'FOR SEPARATING LOW BOILING GAS MIXTURES Filed March 19, 1930 2 SheetS- Sheet 2 INIVENTOR MA TH/AS F R KL ATTORNEYS mixture would tprecipitateas ice or snow in the; tubularcounter-current cold exchangers hitherto; employed and-therebycause stopping up ofthex Theve'xchangers used in the known; processes therefore had :tobe thawed out regu-c longer operating periodyi even if the gas mixture had been previously either? chemically or: thermally treated. fSecondly; .:the.i economy of existing processes "is greatly reduced cold'losses, at least ito be separated has to be compressure than is required'for a large expenditure terrupted.

" larl-y after a a portion of the air of power January 16, 1926 mixture and cold Patented a H T V a 1 LOW PRESSURE rnocnss non snrm'rnzo LOW eommo GAS mx'runes Mathias Frinkl, Augsburg, Germany, American Oxythermie Comration, N. Y., a corporation of Delaware assignor to New York,

p Applicatiriniltarch 19, lsaafseriai No. 431,204

This invention relates to'a process for the sepaf ration of gas mixtures containing lower and higher boiling; components and also other com;

ponents, such as water and carbon dioxide which boil at still higher temperatures and which may; be continuously operated in a simple and CCU-3 nomical manner.

Theseparation of example air, into creased the cost of operation. difliculties arose high boiling components, in the air or other gas apparatus.

shorter or because in-order to cover the pressed to a higher the separation itself, so that in the compressor is necessary. Furthermore, considerable portion (up to about twenty per cent) of the washing liquid which has been liquefied at 3 to 4 atmospheres (i. e. above atmos pheric) is again vaporized when the liquid is-reducedto the lower pressure in the upper rectifier. Finally, all of the prior" processes with the exceptionof that ofLachmann 167,931) are based upon gas mixture to be separated which, as is known;

requires a greater amount'ofpower than partial" liquefaction; The' process oflLachmann' has,

however, thedisa'dvantage that the removal or; dioxide from the mixture moisture and of carbon to' be separatedis rendered very diflicult because a rather large part of the-mixture'is separated The present inventionisan impro which-has No. 1,890,646, in which "ar'igiw'el' process and apps. r'atus is disclosed mixtures. A number of .cold accumulators or regenerators of large cold-absorbingcapacity are employed through which the warm incoming gas separated components are alterlow boiling gas mixtures,-for their main componentsas; heretofore practiced is accompanied by anumber ofdifiiculties which have complicated and in-,

One of the major;v from the fact that the moisture and the carbon di0xide,;.or other comparatively;

a loss of energy arises in that 'a- (German Patent No. total liquefaction of the a v i e my copending application, Serial No. 81,723, flled' now become Patent 'ior separating low boiling v ermany', April 19,1923 10 Claims; (Cl. 82-1755) the same regenerators and through the same packing-filled spaces that:

the cold separated oxygen and nitro en traversed during the previous operating period.

When a gas mixture containing what may be considered high boiling impurities, such as air" which has not been previously treated to remove itsmoisture and carbon dioxide content, or from;

which these substances have been only partially; removed, is conducted to the separating appa-a ratus described-in my above-mentioned application, these high boiling-components (i.- e. the.

water and carbon dioxide) will be deposited in the form of ice and frost such vapor'and carbon lar'gasmixture, is used, it is essentialthat'the ice and frost deposited in the regenerators by the" incoming-gas mixture during any opera be completely sublimed and carried oil by the discharging separated components which pass in the regenerators. When" dioxide-laden air, or

g p riod" through such regenerators during the following" period'when the has been reversed. There-' generators otherwise will gradually become clogged with ice, and the operation of the appa ratus will be disturbed and its continuity in- I have found that and ice in .the can be economically prevented without interruption of operation by so conducting the gas separation process that, among other things, a large the of volume differential exists between the incoming mixture and the discharging separated compo the completeremoval'of the de-'-;

nents. Thereby posited material components as sured; The use of the cold by sublimation by the separated cold regenerators or accumulators flow of the gas mixture and sepa rated components they leave the apparatus is inexchange system o a ing with periodic "reversal andgwith sublimation of the solidified hig boiling impurities is of particular economy when does not have mospheres. otherwise become very every reversal, e. g. about volume of compressed air torsis lost and must be again It isan object of the presenti to be compressed much above "ontopr the gas mixture se The losses'in'compression energy noticeable every threeminutes, the

in the cold accumula-- V vide amethod for-the separationof gaseous'mix tures employing the principle of cold regeneration with periodically reversed operation and in which the accumulation of precipitated high boiling impurities in 'the regenerators (aecumlflators) is 16 due to evaporation during expansion from condenserpressure in a rectifier in which liquid is formed and preliminarily separated to a lower pressure in another rectifier of the separating apparatus are in large measure avoided.

The partial liquefaction of the gas mixture according to my process is apparently in contradiction to the total compression of the gas mixture, for the partial liquefaction should, it would seem, be based upon partial compression. I have found, however, that the removal by sublimation of the frost deposited by the water vapor and carbon dioxide content of the gas mixture necessary makes compressiion of substantially all of "the gas mixture in order to produce the required vol- 80. ume differential between the incoming mixture necessary and the discharging separated components. Accordingly, the removal of the frost has to be accomplished at the cost of the increased power expenditure involved in compressing substantially all of the gas mixture to condenser pressure.

This apparent sacrifice is, however, compensated for in my improved process by'the fact that a portion of the excess of the compressed low 4 pressure .gas mixture, either before or after a preliminary separation with partial liquefaction (if after, then the lower boiling component which,

in air, is the nitrogen) is diverted in the gaseous (or vaporous) state under pressure, and is ex-- 45. panded with performance of work in an expansion engine whereby the cold losses are covered. This quantity of gas is not needed for the formation of the required amount of wash liquid. Theexcess of compressed gas mixture, either as such mixture or'as nitrogen separated by the preliminary separation, thus serves as the operating medium for an expansion engine in which it is expanded with the production of work and cold. It is also employed in the exhaust condition for cooling wash liquid before the latter is expanded and introduced into an upper rectifier of an upper or subsequent separating apparatus.

My improved low pressure process may, as indicated above, be so carried out that an excess of the compressed gas mixture may be expanded in an expansion engine without preliminary separation and may then, in the form of exhaust, be

separated in an upper rectifier, that is by an after or subsequent separaton, so that it may then be 65. conducted, likewise in the form of a lower boiling separated component (e. g. nitrogen), through the wash liquid cooler.

. In practice the invention includes the following four steps compression of substantially all of the 7 gas mixture to a low pressure for the purpose of avoiding theaccumulation of frost by subliming the latter with separated components in the cold 'regenerator through alternate periodical reversed operation; partial liquefaction of the mixture for 75. the purpose of reducing thepower requirement;

Such a method of operation, furthermore, is advantageous because the losses of wash liquid been compressed to about 4 atmospheres becomes the process. Furthermore, only through partial liquefaction can the power requirementbe considerably reduced and this is possible to a full extent and without loss of compressor energy only by a thorough cooling of the wash liquid, for that portion which is vaporized during expansion to the pressure of the upper rectifier causes a useless expenditure of compression energy. a I

As is known, the continuous operation of gas separating plants requires an addition of cold in the form of liquid gas. According to the present process, the. excess of compressor energy expended, when all of the gas mixture is compressed, over and above the amount of energy required for effecting partial liquefaction, is employed to produce additional cold in an expansion engine. This cold output is used to cool the wash liquid'before it is expanded, so that in this way liquid for covering the cold losses is retained, and at the same time a loss of compressor energy by evaporation of wash liquid during expansion is avoided.

The employment of periodically reversed operation with cold accumulators or regenerators is interlinked with the low pressure compression of the gas mixture and with the'subsequent cooling of the wash liquid. Without this cooling a loss of cold in the accumulators could not be avoided because the discharged lower boiling separated component always possesses a temperature which is ten to twenty degrees lower than that of the incoming compressed gas mixture. In the use of continuously operating tubular cold exchangers of any known type, there arises from such fact no disadvantage because the cold excess of the lower boiling component in the form of a lower ,temperature causes in such exchangers a partial liquefaction of the introduced gas mixture. This occurs indeed also in the cold accumulators, but in the latter the liquid cannot be drawn off, since it clings in the form of dew to the surfaces of the lower part of the accumulator pack-, ing when a compressed gas mixture is introduced into accumulators which were previously by a lower boiling component which is cooler by ten to twenty degrees. The dew is, however, immediately evaporated when, upon reversed operation, the accumulator is again under no pressure and this cold if considerable liquefaction occurs in the regenerators is then carried out at the top and lost.

This loss of cold, when air is being separated, may be explained as follows: The air which has liquid at a temperature of l78 0.; the escaping separatednitrogen has, however, a temperature of l96 C. and is thus about 18 colder, so that the cold accumulator through which at any moment nitrogen is being discharged is strong- 15o cooled 35 1,o'ro,soo ly super-cooled ii the output phase is continued too long before reversal, when, upon reversal..- compressed air of 4 atmospheres is introduced into the accumulator a small portion thereof becomes liquefied upon the super-cooled surfaces or the lower part/oi the accumulator packing, and clings to the latter, in the form 0! dew. It. now. the accumulator is again reversed and nitrogen discharged therethrough, the dew immediately completely vaporizes because when under no pressure it can-exist in the condensed condition only at -'-l93., C. or below. Consequently this very considerable quantity of cold may be lost when the cold zone oithe accumulator packing rises constantly higher and hence after some,

time the excess cold of; the lower boiling component (nitrogen-lescapes at the top'. In order to avoid this loss, the lower boiling component, according to the present process, is first brought into cold exchange with the warmer'wash liquid and warmed to approximately the liquefying temperature of the compressed gas mixture.

with myg-improved-process air can be separated into its main constituents by simple compression to 3 to 4 atmospheres without any ire-treatment, and the apparatus required ior carrying out the same includes in combination a low pressure compreesor (for large plants, a turbo-compressor be used an' eirpansion piston engine or turbine, and two pairs of cold accumulators, in addition to the separator for effecting a prelimi inary separation, and a subsequent -rectiflcation. For obtaining commercially pure oxygen only one pair of cold regenerators is necessary and in place 01 the second a counter-current tubular ex- Changes m h us d Heretofore a minimum pressure 01 15 atmospheres was always necessary for theoperation of such plantsin order to provide both for the separation of the mixture and also for covering unavoidable cold loses; or .else, a portion of the gas mixture to be separated had to be compressed to to atmospheres. Such pressures, however. are lmeconmifical for alternating reversedoperation with cold accumulators. Former processes, inrthermore always required a special pro-treatment with chemicals, scrubbing with lye; or cooling, in order toprevent the collection of-frost, and expensive multi-stage compressors had to be provided Turbo-operation was hereto'fore not applicable because of the high preswhen'a separate plant for the production ofadditional liquidair was-not to be erected,

and likewise reversed operation with cold re:

generators tor effecting the coldexchange'is excluded when the operation'goes much'above, 4 atinosphere's, because then the loss of compressed air upon-reversal'-'hecomestoofgreat; floreove'r it' ble unto" the present time, 01 thd'cdl'nplicdtd-"prittreatment of the air mixture with chemicals, d cooling, to operate eidstplants witho terruption -due to freezing. apparatus for the pro-treatment; together 'yz'iththe' compressor plant. increased cost or such pl ts so-muchthat a general introductionof the so aration 'of nitrogen ir'o'm tlieair forjthe operation 'ofiion never m n vom nitrat o -w menswear-p seem-es x e t me i l rllbtioaoi operatiombe vorably the investment cost 0! the plant, as ordinarily reserve apparatus is provided. m the accompanying drawings are illustrate by :way oi. example two. terms lot apparatus i-or flfrrying'out the-present invention; in said draw- I I I I v Figure 1 illustrates diagrammatically a plant embodying the'present invention and employing -.part of the compressed nitrogen in the vapor state. for operating the expansion engine; and

Figure 2 is a similar diagrammatic view showin a plant in which part'oi the compressed air is used as such to operate the expansion engine. The apparatus illustrated in Figure. 1 includes cold regenerators A, A" and-B, B", the evaporator-condenser b, the lower rectifier c' operating at a pressure greater than atmospheric, the upper (artery rectifier c" operating at substantially atmospherlc pressure, the after or super-cooler d for wash liquid and the expansion engine 11.. About three-iourths to four-fii'ths oi the air to beseparated is conducted under pressure to the cold accumulator A through the reversing valve which it enters at k. The air is cooled in such socumulator to --1'l5 C. and is then for the greater part separated in the lowerrectifier 0'. into gaseous nitrogen and-a liquid containing about.40% oxygen. The nitrogenfthenpasse's to the condenser side oi the oxygen evaporator b and irom one-half to three'iourths thereof is liquefied, whereupon the liquid nitrogen is conducted by a conduit 1 to the head. of the upper rectifier c" while the liquid ,oxygen isintroduced at the middie of saidupper reetiflerthrough a conduit 2. a

loo

liquefied under these'conditions, so theta vap r containing about 5 percent of liquid in the form Ioffa mist is produced, whichis then led by a conduit 3 to the cooler d. as indicated at 0. The yield .191 cold that can tliusbe'obtained amounts theo 1- ic'ally to a ca1,,but pt lctically' about 5 CaL/kg. 9 sum obtained, H e e xhaust'nitrogen togetherwith the 'sepa d nitrogenj'i 'om the. upper rectifier passes ugh the cooler d forithe wash and there give 1mm -19.e7 c. to 1so,c, and,thus cools the wash liciiiiidfbrodiicrd at a pressurehf atmospheres, no Theifrebyipartialevapir e n p e ir nft s a eru h o d s ee e ter. s c r set 211-." ft r ii' s in ld it re isgin h.rss eliator. 'Atintervals Q a .f wmhiutes the revere;

. I We are operated j any} suitable manner, for example by a' compressedair engine .(not wnland'the direction or new. or the'incoining' .d. the eni e dsemm nt h u h e to ,g raters is reversed." The compressed air then 9% are co -me e i t"; m t s ni o e 11 th efii e ii uol'ish the'res n re r A r wm nmanner airman regenerators. s' and Ar, al ays takes up a s was to were emu .e v t eair enteritis s up sensible cold. It'rises'in temperature gen passing therethrough in opposie direction during the previous reverse operating period. The oxygen, on the other hand, is alternately Withdrawn through the accumulators B and B" at 11' and n-'. Through these regenerators one-fourth to one-fifth of the compressed air to be separated is alternately introduced at l and 'l" in order to take up sensible cold deposited by the oxygen.

In order to obtain, for example, 250 cubic meters 01' oxygen '0! '15 per cent purity, one thousand cubic meters 01' air are compressed to 3 atmospheresr conducted thiough the regenerators and preliminarily separated into a liquid containing about 40 per cent oxygen and pure nitrogen in the lower (super-pressure) rectifierc. From the rectifier c, 300 cubic meters of nitrogen are conducted to the expansion engine and there expanded to 0.2

air but as the sensible cold of the exhaust nitrogen.

The problem consists now in conserving the sensible cold of the exhaust into liquid. This is -efiected in that the liquid wash is cooled by the cold of the exhaust, together with that of the separated nitrogen fromthe upper rectifier, while the air for the operation of the expansion engine is separated into its main' components by a pressure preliminary separation. Thisseparation of the air for the operation 0 the expansion engine can, however, also. take place subsequently as exhaust. In such case the operating medium of. such engine is not removed as nitrogen in the upper part of the pressure separator 0', but is withdrawn as compressed air from the conduit- (Fig. 2) at point at connected directly to the regenerators. The exhaust .air is conducted to theupper rectifier 0", wherein it is separated. It is only subsequent to this separation that it is conveyed, as nitrogen and form-' ing part of the. total volume of separated nitrogen, through the cooler in order to cool the'wash liquid."

has the disadvantage, as compared with that de-- scribed in connection with Figure 1, in that the separation in the upper rectifier is increased by .the amount of the exhaust'air and the rectification is somewhat disturbed by thepulsatingflow of the exhaust; also, because of the resistance in the rectifier, a "higher exhaust pressure is-opposed to the expansion engine. Furthermore, the use of nitrogen, which has been sepa*- rated in the preliminary separation, has an advantage over air for operating the expansion,

engine because; whereas nitrogen can be'cooled to '196 0., air can be'cooled to only j- 191 C.

This is particularly unfavorable in; the; present case because the wash liquid to be cooled already has a'temperature of 1'80 0., so that a temper--v ature drop of only 11 degrees-with air is available as against 16 degrees when nitrogen is employed to drive the expansion engine. As, however, a temperature diflerence 01 about 5 degrees always exists, then the effective temperature drop is only 11 5=8" for air as against 16-5- 11 for nitrogen. Thus onlyslightly more than 'as with nitrogen operation. As these disadvan 'tages are not'accompanied by equal advantages.

half as useful a yield can be obtained with air then in general, a preliminary-separation or the air isto be carried out, especially as in the operation with non-separated air in the range of saturation a partial liquefaction oi! the oxygen occurs in the expansion engine, which greatly impairs the cold output of such engine.

The prevention 0! irost accumulation by subarated components are discharged through the The operation o1 cold regenerators same space through which they are introduced into the apparatus in the mm 0! the original mixture. This is not, however, the case with con tinuously operated cold exchangers since the inlet and outlet spaces of such apparatus are 'separated from each other by the heat-conducting walls or surfaces.

It will be clear 1mm theabove that, inasmuch.

as in my improvedprocess air or other gas mixture is introduced under a compression of sevare discharged under substantially no pressure,

the volume of such escaping separated components is considerably largerlthan the volume of the incoming mixture. As the capacity of a gas for taking up vapors is a function of its volume and not of its weight, it will be evident that the moisture and carbon dioxide or other high boil-.- ingg impurities deposited by the incoming mixture in the regenerator willbe completely sublimed and carried off by the separated components passing} through the regenerators upon reversal.

Accordingly, in the practice of the invention the high'boiling impurities of a gas mixture are .eral atmospheres, while separated components separated'therefrom in cold regenerators and are a removed therefrom by a subsequent flow in a re.- versed direction of separated components, thus .making it unnecessary to subject gas mixtures The modificationof my novel process in whichsuch as airto expensive pre-treatmentsflto remove the high boiling impurities therefrom.

Where in the claims I-speak of expanding a 1 portion of the mixture, this expression 'is 'to be understood 'to include not only uns'eparated gas.

mixture,.but also a lower boiling component (such as nitrogen) obtained by a preliminary separation.. Variations-may be resorted to within the scope oL-the appended claims without departing from the-spirit oi the invention.- For example, it may not necessary to employ both of the separated coriaponents, to sublime ,the precipitated'frost' and ice; This is particularly so in the case of air, wherein one componentv (nitrogen) preponderates over the other (oiqgen) Thus the component present in smaller quantityneed not be discharged through the regenerators, but may be:

conducted out or the apparatus through a recuperator or tubular exchanger.- Thereby oxygen or other gas, of a higher degree or puritymay be versal: or the oxygen may be withdrawn in liquid I iorm from the apparatus.

It is also to be understood that the iollowing claims are intended to cover all or the generic and specific features of the invention heroine:qi e-z scribed, and all statements oi. the scope of the inventiomwhiclrdas 'a=--matter of -lang iiase'g-"niisht -Milhg. with: periodical reversal, subjecting 's'uch a piellminary separation whereby lower higheni boiling .-'components are produced. and. a-= portion. thereof liquefied whereby.- -.a vwrisirz liquid is; obtained; expanding separated lower boilingcom'ponent :m expansion engine vwith.performance-not=worl: whereby the temperature .--thereo1' 1 reduced, 5 subjecting the expansion .engine, together; with "-lower boiling component discharged during the:after-separatiom-inscoldexchange relation with the wash liquid whereby an excess of wash liquid is obtained and losses of cold obviated.

2. The method of separating gas mixtures which comprises conducting'zatgas'z-mixturethe. entire amount of which is, compressed andwhich contains higher boiling vapors -in contact with ti oh'illed? cold' absorbing body to be precooled thereby with precipitation :of higher boiling va- 1101's, separating such precooled mixture into out-. put components, and efiecting substantially-com plete sublimation or the precipitated vapors by Q l lQ nE-; FP- i l d, .0 tP} .l 99I P9P e pafridd co'ndi oh in"i-'ve" ture into hig le I -ii go'we'r' boiling output comhigherhoiling vapors had .,previou sl y been. de-

.3. The "inetliod'of separating as mixtures i -h ompr estim sea entire amount of which is com re edand whi contains higher boiling vapors in a chilled cold absorbinghbdy to? be) precooled' thereby with precipitation of higher boiling vapors, partially liqueiying such mixture to produce a quantity oi wash liquid, separating said mixcontains higher boiling vapors in contact witha chilled cold absorbing body to be precooled there by'with p ecipitation of higher boiling vapors, partially 1i uefying such mixture, expanding an unliquefied portion of the mixture with performance of-external work whereby the temperature .thereoi is=.reduced and cooling 0. part of the mixture therewith-whereby cold losses are covered,

' separating said into output components,

and effecting substantially complete sublimation of the precipitated vapors byconducting separated output components in expanded condition in reverse direction in direct contactwith a "tire contact wanom 'ge'n s b e ndd'y; 1iquety-' a '="ing"-a-portion=-of suc whereby' ia wash g -gas mixturesthe H -'tioh tit-the gas mixture-withperformance Mex-=- workwhereby' the' temperature of such mixture iii-reduced; and copling-said-wash liquid by -conductin'gi'tm heat-exchange' relation" with tures containing 'highef boiling vapors which 'inixtureto. an .-aiter.-separation whereby a furtherse paration into -.lower. and vhigher boiling com-- --:p0nents j:takes= place, and monductinglower boil-- .ing component :in expanded condition "from the .fcold j-iabsorbing body 'upon which cold absorbing body D 11 which higher boiling vapors had previously been deposited.

:5. The method or separatins sas mixtures whioh con prises cooling ages mixture the en-- mount which-is-'-conifiressedjby direct so liquid isobtamedi expanding" "anunli'quefied porthe-expanded portion;

- 6.--The method for the separation oi. gas mix- .90 comprises-:conductingsuch'a gas mixture through "cold regenerators wherein-the mixture'is chilled and "deposits -higher--boiling vapors, separating such mixture into output components, periodical- 1y reversing the-"flow through the reg'enerators,

and eflecting a substantially-complete sublimation of the .vapors deposited'inthe regenerat'o'rs from the gas mixture during inflow by conducting sepingymoisture and carbon dioxide therefrom by no contacting with a cold, solid regenerative mass, separating the chilled air into nitrogen-enriched an owseneenrichedou put comp n n nd "substantially' completely'subliniing the deposited s;

-moisturerandcarbon-:.:dioxide from a regenerahe s b cor du tin nitme w mich put component contact therewithin a iiirection='reverse "to that" of the inflow of air,

th 10 ie it e -en che component W terthanthe volume of air 12 previously contacted said regenerative mass "to eifect substantiallycomplete sublimation of the deposited vapors.-

8. In a process for the separation of air, the .5;

method for the removal of higher boiling vapors such as moisture-and carbon dioxide, which in- 'cludes in combination, compressing air, depositing higher boiling vapors by condensation" and solidification upon a solid thermal regenerative mass previously cooled to a temperature suii'i- 1m cientl'y low to efiect said condensation and solidification by passing said air over and in direct contact with the chilled regenerative mass in regenators, separating the thus chilled air into an oxygen-enriched and a. nitroge'n-enriched135- fraction, and simultaneously passing separately through other regenerators in contact with a similar'thermal regenerative mass, the oxygenenriched and nitrogen-enriched fractionsat less compression and in suflicient volume to eiiect a 1 substantially complete removal by sublimation of suchhigher boilingvapors deposited upon the regenerative masses, frequently and rapidly repeating phases'which reverse as between said regenerators the direction of flow and the funcitions of said regenerators without substantially interrupting the use of said .masses to thaw out said regenerators.

9. In a process for the separation of air, the method for the removal of higher boiling vapors such as moisture and carbon dioxide, which ineludes. in combination,- compressing air, depositlug higher boiling vapors by condensation'and solidification upon asolid thermal regenerative substantially complete removal by sublimation of such higher boiling vapors deposited upon the regenerative mass,

frequently and rapidly repeating phases which reverse as between said regenerators the direction of flow and the functions 01' said regenerators without substantially interrupting the use 01' said masses to thaw out said regenerators; the volume of the oxygen-em- Patent No. 1,970, 299.

CERTIFICATE or CORRECTION.

rich'ed and the nitrogen-enriched fractionsbeing greater than that of the input air'previouslr chilled by the respective regenerative mass with which each fraction contacts.

10. In the method for the separation of gas mixtures by cooling, the step or removing im'-. purities which condense at relatively high temperatures which comprises conducting said gas; mixture the entire amount 0! which is subjected to compression through cold regenerators and at the same time conducting" separated co'm- 8 ponents through other cold regenerat'ors in the opposite direction, and periodically reversing the flow through said regenerators, the. volume of the component flowing in a direction opposite to the gas mixture being greater than that of the gas mixture which passed through the regenerator during a given previous period, whereby constituents oi the gase'ousmixture deposited in said regenerator are completely removed in agaseous phase.

' August 14. 1.934.

mums FRANKL.

, ltj's her'eby certified that error appears in the printed specification of the above numbered patentrcquiringoorrection as follows: Page 2, lines 271ml 31'. strike out 'the word "llccessaryfi and. line 2?, after "mixture" insert theword, necessary; page 4, line 30, strike-out'the words into liquid"; and that the said Letters Patentshould be' read'with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 9th day of October, A; D.-. 1934.

Leslie-Fraser Acting Commissioner of Patents such as moisture and carbon dioxide, which ineludes. in combination,- compressing air, depositlug higher boiling vapors by condensation'and solidification upon asolid thermal regenerative substantially complete removal by sublimation of such higher boiling vapors deposited upon the regenerative mass,

frequently and rapidly repeating phases which reverse as between said regenerators the direction of flow and the functions 01' said regenerators without substantially interrupting the use 01' said masses to thaw out said regenerators; the volume of the oxygen-em- Patent No. 1,970, 299.

CERTIFICATE or CORRECTION.

rich'ed and the nitrogen-enriched fractionsbeing greater than that of the input air'previouslr chilled by the respective regenerative mass with which each fraction contacts.

10. In the method for the separation of gas mixtures by cooling, the step or removing im'-. purities which condense at relatively high temperatures which comprises conducting said gas; mixture the entire amount 0! which is subjected to compression through cold regenerators and at the same time conducting" separated co'm- 8 ponents through other cold regenerat'ors in the opposite direction, and periodically reversing the flow through said regenerators, the. volume of the component flowing in a direction opposite to the gas mixture being greater than that of the gas mixture which passed through the regenerator during a given previous period, whereby constituents oi the gase'ousmixture deposited in said regenerator are completely removed in agaseous phase.

' August 14. 1.934.

mums FRANKL.

, ltj's her'eby certified that error appears in the printed specification of the above numbered patentrcquiringoorrection as follows: Page 2, lines 271ml 31'. strike out 'the word "llccessaryfi and. line 2?, after "mixture" insert theword, necessary; page 4, line 30, strike-out'the words into liquid"; and that the said Letters Patentshould be' read'with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 9th day of October, A; D.-. 1934.

Leslie-Fraser Acting Commissioner of Patents 

